Since the start of the Iran conflict, President Trump warned that the regime’s days were numbered, culminating in this week’s threat to obliterate Iran’s “whole civilization.” But for more than a month, the Iranian regime held out under relentless bombardment by the strongest military power in the world before reaching a cease-fire with the U.S. that could ultimately see Iran maintaining influence over one of the world’s most important sea lanes. Iran’s ability to resist despite large civilian casualties, the decapitation of much of the regime’s leadership and severe economic damage shows the staying power of authoritarian governments. For decades,...